This invention relates to reducing electrical signal interference and return loss which arises due to parallel contacts in electrical connectors. More particularly, it relates to reducing return loss and pair to pair as well as common mode cross talk interference in FCC type plugs. The Federal Communications Commission has adopted certain architectural standards with respect to electrical connectors utilized in the telecommunications industry so as to provide intermatability. The connectors most commonly utilized are FCC type modular plugs and jacks, also referred to as RJ45 plugs and jacks. The plug is commonly terminated to a plurality of conductors which may be connected to a communication device. Normally, each plug is terminated to eight conductors which form four pairs. The corresponding jack is commonly mounted to a panel or a printed circuit board or a wall outlet, which in turn is connected to the telecommunication network. To complete the circuit, the plug and jack are intermated.
While most of the cross talk and return loss problems arise in the plug, normally the reduction of cross talk and return loss is dealt with in the jack. For example, U.S. Pat. No. 5,299,956 assigned to Optical Cable Corporation, assignee of this application, shows a jack connected to a circuit board in which traces on the board are used to cancel cross talk which primarily arises in a corresponding plug. U.S. Pat. No. 5,310,363, also assigned to Optical Cable Corporation, shows a similar jack having both cross talk cancellation and return loss reduction features.
Industry standards for maximum cross talk, both near end cross talk (NEXT) and far end cross talk (FEXT), common mode coupling, and maximum return loss are governed by the Telecommunications Industry Association (TIA). The TIA is currently addressing performance standards at the so-called Category 8 level, which is in a bandwidth of up to 2,000 MHz and designed to enable data transmission rates up to 40 Gbits per second. The TIA standards are pair and frequency dependent. The TIA standards as currently drafted for NEXT, FEXT and return loss for various frequencies and pairs are shown in the graphs illustrated in FIGS. 6 through 14.
As previously stated and as taught in Optical Cable Corporation's U.S. Pat. No. 5,299,956, cross talk compensation is normally primarily carried out on a circuit board which is attached to the jack. A properly designed plug, however, is essential so as not to degrade the cross talk cancellation features of the jack and, in addition, to ensure minimal return loss.